What's So Bad About High Fructose Corn Syrup?

The truth behind the buzz about this controversial sweetener.

“It’s natural, nutritionally the same as table sugar and has the same number of calories,” say ads for high-fructose corn syrup (HFCS). Others call the sweetener “a growing health hazard,” “naturally evil,” and worse. For now, the naysayers seem to be winning: the number of foods flaunting “No HFCS” labels is rising steadily. Even Snapple and Pepsi recently launched new beverages sans HFCS. But what’s the truth about HFCS? Here’s what we found when we looked at the science.

Is HFCS the main culprit in the obesity epidemic?

The theory sounded logical in 2004, when an article in the American Journal of Clinical Nutrition proposed it. The study’s authors—including Barry Popkin, Ph.D., director of the University of North Carolina, Chapel Hill’s Interdisciplinary Obesity Center—pointed out that from 1970 to 1990 Americans’ intake of HFCS increased by more than 1,000 percent. The researchers also noted that, during that same time, the proportion of Americans who were overweight or obese increased from about half to two-thirds.

Singling out HFCS turned out to be unjustified, Popkin now admits. “Dozens of human studies on HFCS and energy intake and weight change show that our hypothesis was wrong.” The American Medical Association came to a similar conclusion last June, when it announced: “High-fructose corn syrup does not appear to contribute more to obesity than other caloric sweeteners.”

So why are so many more Americans overweight? For one, we’re eating more, period: the latest U.S. Department of Agriculture estimates show that, since 1970, our daily calorie intake has grown by a whopping 24 percent. Sweetened beverages have added a huge quantity of calories to our diets. “More than 450 of a person’s daily calories come from beverages, 40 percent from soft drinks or fruit juices,” says Popkin. Studies show that when we consume calories in liquid form our bodies don’t acknowledge them the way they do those from solid food and we don’t cut our food intake later. So should we blame HFCS, since it sweetens most sodas and sweet drinks? That’s guilt by association, not a direct cause, says Popkin. “Sugary beverages are the culprit, and whatever form the sugar is in does not matter.”

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Do studies show that HFCS amps up your appetite?

People often confuse HFCS with plain fructose and, in fact, a number of studies in animals and humans suggest that consuming pure fructose may not satisfy hunger the same way pure glucose does.

Both fructose and glucose trigger reactions in the body that eventually lead to feeling full, says Kathleen Melanson, Ph.D., R.D., a professor of nutrition and food sciences at the University of Rhode Island. But glucose does this more efficiently. When you consume glucose, the pancreas releases insulin, which, in turn, causes an increase in leptin, a hormone that tells the brain we’ve eaten enough. Glucose also blunts the effects of ghrelin, a “hunger hormone” that makes us want to eat more. Pure fructose doesn’t activate these same “fullness” cues, explains Melanson.

But high-fructose corn syrup isn’t pure fructose (100%-fructose foods don’t exist outside of the laboratory; neither do 100%-glucose foods). High-fructose corn syrup is half fructose and half glucose—just like table sugar is. And, because they both contain glucose, HFCS and table sugar do activate leptin and ghrelin systems, says Melanson. In fact, they seem to affect them very similarly.

In a 2007 study of 30 women, Melanson and her colleagues looked at whether drinks sweetened with HFCS affected appetite differently than drinks sweetened with sucrose. They found no differences in the women’s insulin, leptin and ghrelin levels—or in the women’s own ratings of hunger. (Critics have carped that PepsiCo helped support the research, but the findings haven’t been disputed, and other studies show similar results.) “There’s no evidence to date that HFCS affects appetite any differently than sucrose,” agrees Karen Teff, Ph.D., a physiologist at Monell Chemical Senses Center in Philadelphia who has also studied this issue extensively.

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Does all HFCS contain mercury?

In January, consumers received a double dose of troubling news about HFCS and mercury, the heavy metal that even in small amounts poses a neurological risk for young children, babies and growing fetuses. First, a study in Environmental Health reported that mercury was found in nine of 20 commercial samples of HFCS tested in 2005. Then the Minneapolis-based nonprofit Institute for Agriculture and Trade Policy (IATP) reported that it had found “detectable levels of mercury” in 17 of the 55 HFCS-rich foods it tested last fall, including barbecue sauce and cereal bars.

The reports raised the possibility that foods other than fish may contain mercury. “Even if only a small portion of HFCS is contaminated, that’s a really important source of exposure we hadn’t counted on,” says IATP’s David Wallinga, M.D., an author of both studies.

But the studies could not connect the dots on how the mercury got into the HFCS or the foods. The authors theorized that it came from caustic soda, an ingredient used to make HFCS. Although about 10 percent of U.S. plants that produce caustic soda use a process that includes mercury, Audrae Erickson, president of the Corn Refiners Association (CRA), is adamant that no mercury-based technology is used in North American HFCS production. “The [Environmental Health] report is based on outdated information,” she says. In late March, the CRA issued a report indicating that third-party testing on HFCS from all production plants in the U.S. and Canada did not find detectable levels of mercury in any of the samples analyzed.

It is conceivable that the mercury IATP detected in the foods could have come from sources other than HFCS. Mercury is ubiquitous in our environment: it’s in water and soil. What we can say with certainty at this point is that mercury isn’t required to make HFCS, and not all HFCS contains mercury.

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Does HFCS make kids more “hyper” than other types of sugars do?

When it comes to the effects of sweeteners on children’s behavior, there will always be a chasm between what’s reported in clinical trials and what’s reported at a 6-year-old’s birthday party. “Ask any parent at that party, and they’ll tell you the kids are bouncing off the walls from all the sugar in the soda, cake and candy,” says Keith Ayoob, Ed.D., R.D., a pediatric nutritionist and an associate professor of pediatrics at Albert Einstein College of Medicine in New York. “But the reality is that they’re 6-year-olds at a party. It’s situational, not due to the sweets.”

Among the dozens of studies over the past few decades that have looked at the effects of sugars, Ayoob says, none have been able to show that sugar of any kind causes or aggravates behavior problems, including Attention-Deficit/Hyperactivity Dis­order (ADHD). The idea that HFCS affects kids differently than table sugar hasn’t been studied but it’s not likely, he says, “since [the sweeteners’] chemical compositions are virtually the same.”

Roseanne Schnoll, Ph.D., R.D., an associate professor of health and nutrition sciences at Brooklyn College of the City University of New York, agrees that HFCS and sugar are similar enough that “as far as kids’ behavior is concerned it doesn’t really matter [which] kids are getting.” But she doesn’t think the case is closed when it comes to sweeteners and behavior. Schnoll says that many studies that have exonerated the sweet stuff observed kids after giving them only 13 to 15 teaspoons of sugar—little more than what’s in a 12-ounce can of soda—and notes that, today, some kids consume the equivalent of 50 teaspoons a day. Both Ayoob and Schnoll advise minimizing all added sugars in kids’ diets, to help prevent “empty” calories from adding up and displacing other, healthier foods.

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Can “natural” or “organic” products contain HFCS?

A “natural” granola bar or fruit drink may contain HFCS but an “organic” one cannot—at least until someone invents USDA-certified organic HFCS.

The Food and Drug Administration’s definition of “natural” doesn’t have the regulatory teeth that the USDA’s definition of “organic” does. The agency requires only that natural products contain “nothing artificial (including artificial flavors) or synthetic (including all color additives regardless of source) that would not normally be expected in the food.” Last year, the Corn Refiners Association petitioned the FDA, arguing that though a synthetic agent (glutaraldehyde) is used to make HFCS, it does not come into contact with the sugars. In response, the FDA allowed that, when made by the process the CRA described, HFCS fits the criteria for “natural.” This decision cleared the way for manufacturers to request “natural” claims on foods containing HFCS.

Certainly, you could argue that “natural” does not seem an appropriate descriptor for HFCS—or for table sugar. Neither occurs in nature in the forms we use them in. Both need plenty of heating, filtering and centrifuging to extract a finished product. HFCS is processed repeatedly with enzymes; sugar is refined using calcium hydroxide or phosphorus.

From an environmental standpoint, HFCS production may have a slightly more negative impact than does sugar, says Jason Clay, Ph.D., senior vice president of markets for the World Wildlife Fund in Washington, D.C. Producing both sweeteners uses similar amounts of water, but HFCS requires more energy and nitrogen fertilizer, he explains. “It also takes a lot less land to grow the same amount of sweetener with sugarcane than with corn.”

Bottom line: To date, the research suggests that high-fructose corn syrup and table sugar aren’t that different: they’re both processed sweeteners that add “empty” calories to our diets. Our bodies seem to treat them the same way. At EatingWell, we try to limit sweeteners of any kind in recipes. Whenever possible, we use ingredients that don’t contain HFCS.

It’s true that, compared to other types of sugars, large doses of fructose can cause stomach upset, even in healthy people. That’s even truer in patients with IBS, a condition whose hallmark symptom is recurring gastrointestinal (GI) distress. “Fructose empties from the stomach more rapidly than other sugars, and it’s more slowly absorbed [from the GI tract into the blood] than glucose,” explains Peter Beyer, R.D., an associate professor of dietetics and nutrition at the University of Kansas Medical Center in Kansas City. A big hit of fructose—such as what you’d get in a giant serving of apple juice—can overwhelm your body’s capacity for absorbing it. Thus, it lingers undigested in your GI tract where it can cause gas, bloating and general GI distress.

But this generally isn’t an issue when fructose is combined with glucose, as you’d see with high-fructose corn syrup, and with sucrose, says Beyer. In fact, a recent study showed that when scientists gave healthy people and IBS patients a large dose of fructose and, on a separate occasion, a large dose of HFCS, both tolerated the HFCS solution better.

That said, with any sugar, “the poison is in the dose,” says Beyer. And, while there’s no evidence that IBS is caused by sweeteners, “people with IBS are more likely to be sensitive to any sugar than other individuals,” he notes. “HFCS is no worse in that regard.”

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Glossary of Sugars

Glucose

A so-called “simple” sugar naturally found in all foods that have carbohydrate. Starch (e.g., in potatoes, pasta) is many glucose molecules linked together.

Fructose

Another simple sugar, fructose is often called “fruit sugar” because it’s the main type of natural sugar in fruits (and honey).

Sucrose

Corn Syrup

A syrup used mostly in baking that’s virtually all glucose; it’s made by extracting and breaking down starch from corn into separate glucose molecules.

High-Fructose Corn Syrup

First available in 1967 and used by commercial food manufacturers, it’s made by converting some of corn syrup’s glucose into fructose. High-fructose corn syrup is high in fructose only in relation to plain corn syrup; chemically, it’s very similar to sucrose: about 50/50 glucose and fructose.